Characterization of the B cell-macrophage lineage transition in 70Z/3 cells

The 70Z/3 cell line is able to undergo lineage conversion from a pre-B to macrophage phenotype. Data presented here show that the transition from pre-B to macrophage follows a reproducible pathway via a stable intermediate stage. The cells in the intermediate stage are adherent and have lost the ability to respond to lipopolysaccharide or interferon-gamma by induction of immunoglobulin kappa light chains. However, these cells do not yet display the full range of macrophage-specific properties such as receptors for macrophage-colony stimulating factor or the beta 2 integrin CD11b/CD18. Subcloning experiments with the intermediate cells revealed that they retain the options of either persisting along the macrophage line of differentiation, acquiring additional macrophage traits, or reverting to the pre-B phenotype. Further differentiation to the macrophage stage is accompanied by the apparent loss of the ability to revert. Thus, these studies define relationships among lineage-specific traits, and begin to reveal critical stages in lineage commitment.